The disclosure relates to ion exchangeable alkali aluminosilicate glasses. More particularly, the disclosure relates to alkali aluminosilicate glasses that undergo rapid ion exchange.
It has been found that the resistance of chemically strengthened glasses to damage during drop testing (i.e., dropping the glass from a prescribed height) is affected by the depth of the surface compressive layer achieved by chemical strengthening. To date, glasses are chemically strengthened to the extent that the resulting central tension does not exceed a limit beyond which delayed failure occurs.
However, it has also been found that for some glass compositions mechanical properties increase with increasing central tension. Highly frangible glasses beak spontaneously with no delayed failure.